Just finished listening to the 40th anniversary edition.
The novel - structure, the writing, etc. - is far better than I'd expected.
And Blatty's reading of his own novel is FAR better than I expected - his reading is actually in WOW! SERIOUSLY? WHY DIDN'T ANYONE TELL ME? territory.
It's a pretty incredible audiobook - myriad voices, all performed not just well, but enthrallingly - and the story holds up despite its familiarity.
(But maybe I should have expected this - Because I was in a situation where it happened to be the only decent-looking book around, I read his sequel, LEGION, probably 30 years ago and really enjoyed it, and the movie based on that, EXORCIST III, directed by Blatty, is totally in WOW! SERIOUSLY? WHY DIDN'T ANYONE TELL ME? territory too - an opinion I've held for years now.)